This invention relates to valve apparatus which is useful in testing a string of tubing in a well bore.
In some earth well treatments very high pressures are applied to the string of tubing which is run into the well to the depth at which the treatment is to take place. A so-called tubing tester is attached between the bottom of the tubing string and a packer.
Periodically, as the tubing is lowered into the well casing, the tubing is pressurized to determine if it can withstand the treating pressure.
The tubing tester permits fluid to pass up the tubing as the tubing is lowered into the casing which is partially filled with fluid, permits a spring loaded flapper valve to close when pressure is applied to test the tubing, and positively opens the flapper valve when the pressurized well treatment begins.